The present invention concerns a roller bearing with a lubricating device for the inner raceway.
It concerns more particularly the case wherein for technical reasons it is impossible or very difficult to directly lubricate the inner raceway of the bearing.
It is known that roller bearings of the type used in gas turbines of aircraft engines to support a first shaft with respect to a second shaft contain an inner race mounted on the first shaft, an outer race mounted in a bore of the second shaft and rollers located between the inner and the outer races spaced regularly by a separator or cage.
The solution generally used for the lubrication of such bearings consists of introducing the lubricant directly to the inner raceway by means of jets or through a bore of the inner shaft. Under the effort of the centrifugal force, the lubricant is forced toward the outer raceway of the bearing so that the latter is suitably lubricated.
As an example of this solution, the roller bearings described in U.S. Pat. No. 3,722,967, filed Oct. 26, 1971, in the name of Harry L. LEWIS, may be cited.
This patent describes a bearing containing a device for the lubrication of the inner raceway. Oil, coming from a storage reservoir, is projected onto the inner raceway at the base of the rollers. Under the effect of the centrifugal force, the oil passes through the cage which maintains the regular spacing of the rollers and is deposited on the external raceway of the bearing.
It is then recovered in circular grooves provided on the outer race and recycled to tlhe storage reservoir.
However, it is not always possible to conduct the lubricant to the inner raceway of the bearing, particularly in certain advanced turbojet engines wherein an intershaft roller bearing effects the centering of the high pressure spool on the low pressure spool. It is therefore necessary to apply the lubricant to the external raceway, which under these conditions is suitably lubricated. In contrast, the inner raceway is poorly lubricated and the removal of heat is not assured, the more so since the centrifugal force is opposed to the motion of the oil from the outer raceway to the inner raceway.